The influence of habitat on fat storage by Greater Snow Geese (Chen caerulescens atlanticus) on their St. Lawrence River estuary spring staging grounds was studied in 1979 and 1980. In all, 373 individuals (two-year old and older birds only) were collected in two types of marsh during the six-week staging halt: the traditionally-occupied fresh-water, Scirpus-dominated marshes of the upper estuary (SCI) and in the newly-invaded (after the early 1960s) salt-water, Spartina-dominated marshes (SPA) of the lower estuary. The birds reached SPA a few days later than SCI in early April, at which time their total fat reserves amounted to about 10% of their body weight. Fattening at SCI increased steadily throughout the staging period, while at SPA, it slowed markedly in females and stopped completely in males around the middle of the staging period. In birds departing for the arctic around 18-20 May, the total fat reserves amounted to 19-20% of the body weight. Males departing from SCI carried 23% more fat on the average than those of SPA (P < 0.01), while the difference amounted to 90% in females (P > 0.05). It appears unlikely that the geese could increase these reserves after leaving the St. Lawrence estuary and before reaching their high-arctic nesting grounds.
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Gauthier et al. (1984) studied this question.